Major Air Pollution Events: A Historical Perspective

Air pollution is one of the most significant threats to human health and the environment, causing approximately 5.5 million premature deaths worldwide. While air pollution is not a new issue, with instances dating back to ancient Rome and 13th-century London, it has become an increasingly pressing concern due to industrialization, economic growth, and population increases. Some notable events that have caused severe air pollution include the Great Smog of London in 1952, which led to an estimated 8,000-12,000 deaths and the implementation of the Clean Air Act, and the Donora Smog crisis in the US, considered one of the worst air pollution incidents globally. Additionally, the burning of coal in St. Louis, MO, resulted in what was known as Black Tuesday, where the city was shrouded in darkness due to poor air quality. Climate change, caused by carbon and greenhouse gas pollution, is expected to lead to more intense hurricanes, storms, flooding, droughts, and severe wildfires, causing deaths, injuries, and property damage. The COVID-19 pandemic also highlighted the correlation between mortality rates and long-term exposure to air pollution, with higher death rates in areas with more particulate matter pollution.

The Great Smog of London, 1952

The smog caused major disruption, reducing visibility and penetrating indoor areas. It brought London to a near standstill, with severe restrictions on transportation, ambulance services, and cultural events. The immediate effects included a spike in deaths and hospitalizations related to respiratory issues, with government medical reports estimating up to 4,000 deaths directly linked to the smog and 100,000 people falling ill. However, the long-term impacts were also significant. Research suggests that the total number of fatalities was much higher, with estimates ranging from 10,000 to 12,000. Individuals who were foetuses or infants during the smog were found to have lower intelligence and worse respiratory health later in life.

The Great Smog of London highlighted the seriousness of air pollution and prompted Parliament to pass the Clean Air Act in 1956, marking a turning point in the history of environmentalism. Financial incentives were offered to encourage households to move away from open coal fires, and the Act led to a reduction in air pollution. This event also served as a backdrop for various literary and artistic works, including novels, a Doctor Who audio play, and an episode of The Goon Show.

The Great Smog of London was not an isolated incident, and smog continues to be a problem in cities worldwide, such as Mexico City, Beijing, and Los Angeles. Air pollution, primarily from the combustion of fossil fuels, has severe health and environmental consequences. It contributes to respiratory diseases, cardiovascular issues, lung cancer, and premature deaths. According to the World Health Organization (WHO), nearly seven million deaths worldwide each year are attributed to indoor and outdoor air pollution.

Donora Smog crisis, US

The Donora Smog crisis of 1948 is considered the worst air pollution disaster in U.S. history. The incident, which took place in Donora, Pennsylvania, is known for its devastating impact on the community and its role in highlighting the dangers of air pollution, ultimately influencing the development of environmental protection policies in the United States.

Donora, a small town nestled in a narrow valley along the Monongahela River, was home to approximately 14,000 residents, many of whom were employed by the local steel and zinc industries. These industries, while providing economic opportunities, also emitted significant amounts of pollution. On October 27, 1948, a temperature inversion occurred, trapping the pollution in the valley. The stagnant air acted as a lid, preventing the dispersal of harmful pollutants.

The result was a thick, yellowish smog that blanketed the town for several days. This smog was a mixture of smoke, fog, and pollutants, including hydrogen fluoride, sulfur dioxide, nitrogen dioxide, and fluorine, among other poisonous gases. The air pollution caused respiratory distress among residents, with many experiencing coughing and difficulty breathing. The first death occurred in the early hours of October 30, and by the time the smog cleared on October 31 due to rainfall, an estimated 20 people had lost their lives, with 5,900 others affected—a significant proportion of Donora's population.

The Donora Smog crisis sparked a public health and environmental crisis, drawing attention to the deadly consequences of air pollution. It prompted the first large-scale epidemiological investigation of an environmental health disaster in the United States, leading to increased awareness of the long-term effects of pollution, including higher rates of cardiovascular disease and cancer in the region. The event also inspired the Clean Air Act and highlighted the need for industrial regulation, sparking a national conversation about balancing economic interests with the health and well-being of communities.

The aftermath of the Donora Smog crisis saw legal repercussions, with lawsuits filed against U.S. Steel and American Steel and Wire, the operators of the plants responsible for much of the pollution. While the companies settled, they never accepted full responsibility, attributing the event to "freak weather conditions." The crisis had a lasting impact on Donora, with property values declining and residents facing the challenge of rebuilding their community while advocating for improved air quality and environmental protection.

COVID-19 and particulate matter

COVID-19 is a respiratory disease that primarily affects the lungs. Fine particulate matter is an air pollutant that can damage pulmonary tissue. Long-term exposure to fine particulate matter air pollution has been linked to an increased risk of lung diseases and other medical conditions.

During the COVID-19 pandemic, studies found a correlation between higher COVID-19 case numbers and long-term exposure to fine particulate matter air pollution. Research from Germany showed that an increase in the average long-term air pollution of 1 μg/m3 particulate matter PM2.5 was correlated with 199.46 more COVID-19 cases per 100,000 inhabitants. Similarly, a study from Harvard's T.H. Chan School of Public Health in 2020 showed that COVID-19 mortality rates were higher in areas with more particulate matter pollution. This correlation between the virus's deadliness and long-term exposure to air pollution was also observed in India.

There are two potential mechanisms that may explain the causal relationship between fine particulate air pollution and SARS-CoV-2 infections. The first is that particulate matter may act as a carrier for the airborne virus, transmitting it into the human respiratory system. The second is that fine particulate matter could increase the severity of COVID-19 by delaying or complicating recovery. For example, fine particulate matter can worsen bronchitis, lead to heart attacks, and cause other cardiovascular issues.

The combination of the COVID-19 virus and fine particulate matter air pollution may exacerbate the virus's impact on human health. While more epidemiological investigations are required to confirm the causality of particulate matter air pollution for COVID-19 cases and severity, the existing evidence suggests that reducing air pollution is beneficial for both climate and health outcomes.

Furthermore, it is important to note that certain communities, including low-income communities and communities of color, are disproportionately affected by air pollution due to the historical siting of highways and polluting facilities in or near their neighborhoods. As a result, the negative health consequences of air pollution, such as increased COVID-19 cases and mortality, have been more severely experienced by these communities.

Industrialisation

The burning of coal and other fossil fuels in factories and homes in industrial cities released harmful pollutants into the atmosphere, leading to thick smog that covered these urban areas. The Great Smog of 1952 in London, caused by a combination of coal-burning and an anticyclone weather event, is a notable example of the impact of industrialisation on air quality. The smog blanketed the city, causing respiratory illnesses and harming wildlife.

The increased demand for coal and other natural resources during industrialisation led to the exploitation and depletion of these non-renewable resources. Improper mining practices also contributed to air pollution, as toxic pollutants ran off into waterways, and deforestation altered habitats. The trend of wastefulness and overconsumption further impacted the environment, with industrial cities becoming heavily polluted with smoke, soot, oil, and debris.

Various industries, such as fracking-related infrastructure, steelmaking plants, petrochemical plants, and hazardous waste sites, continue to be significant sources of industrial air pollution. The natural gas, plastic, chemical, electric generation, and waste disposal industries can generate hazardous waste that, if not properly disposed of, can create significant air pollution. The Clean Air Council and similar organisations work to reduce air pollution from these industrial sources, advocating for policy changes and community education to address the issue.

Fossil fuels

Particulate matter, specifically PM2.5 (fine particulate matter with an aerodynamic diameter of less than 2.5 μm), is of particular concern. PM2.5 particles are tiny, about one-thirtieth the width of a human hair, and can linger in the air for extended periods. These particles are easily inhaled and can penetrate deep into the lungs, entering the bloodstream and causing damage to multiple organs. The health impacts of PM2.5 are especially severe for children, older individuals, those on low incomes, and people of colour, with urban areas often experiencing the worst effects.

The combustion of fossil fuels has been linked to a range of adverse health outcomes, including respiratory diseases, heart disease, lung cancer, and asthma attacks. It is also a contributing factor to climate change, leading to increased temperatures, melting glaciers, and rising sea levels, and more frequent and intense hurricanes, storms, flooding, and droughts.

According to recent studies, air pollution from fossil fuels is responsible for a significant number of premature deaths worldwide. The Global Burden of Diseases, Injuries, and Risk Factors Study 2015 estimated that exposure to PM2.5 caused approximately 4.2 million deaths globally. However, a more recent study published in Environmental Research put the death toll at 8.7 million in 2018, with China and India accounting for nearly five million of those deaths. Another study, using the GEOS-Chem chemical transport model, estimated global premature mortality due to fossil fuel combustion at 10.2 million per year in 2012.

The high death toll associated with fossil fuel pollution has led to increasing pressure on world leaders to take action. Phasing out fossil fuels and transitioning to clean, renewable energy sources are crucial steps in reducing air pollution and mitigating the impacts of climate change.

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